Natural wicker has been used in the manufacture of furniture, baskets and other articles for many centuries. The casual, informal appearance of wicker has made it especially popular for use in enclosed porches and other informal settings in homes, hotels and other establishments. Natural wicker, however, has had limited use in the outdoor furniture market, including patio furniture, pool furniture and the like. This is because natural wicker softens and weakens when wet, and is more susceptible to rotting and mildew than many other natural and man-made furniture materials.
Woven wicker typically comprises a weft yarn, i.e., a yarn running straight through the woven material, and a warp yarn, i.e., a yarn that is woven around the weft yarn. Numerous styles of weave are used in the manufacture of wicker furniture. The various styles of weave result in a different look, feel, strength and weight of the finished woven product. In a simple weave pattern, the weft yarns are spaced apart and arranged parallel to each other. The warp yarns are woven over and under alternating weft yarns. Adjacent warp yarns pass on opposite sides of a given weft yarn.
Polymer yarns have also been used to manufacture wicker-like furniture. By way of example, a polymer yarn is known which is constructed as an elongated body, such as of indeterminate length, having a core surrounded by a sheath of polyvinylchloride (PVC) outer coating, for example, foamed and non foamed PVC material. Foamed PVC material gives greater volume with less material. The outer coating may be formed of other synthetic materials such as polyamides, polyesters and the like. The yarn is typically made in a single step using a coextrusion process, as is known in the art. The inner core may include a single filament of polyester, or may include a plurality of polyester filaments bundled to form a single core. In addition, the core may be formed of other materials than polyester such as metal, monofilament or stranded, such as polyamides and the like. The core is designed to give the yarn greater mechanical strength over yarns formed only of polymer material. This is considered more important when the outer layer is constructed from foamed polymer material.
The polymer yarn being constructed from foamed PVC material results in a lack of uniformity in the foaming of the PVC material during the extrusion process. This produces a yarn which lacks a uniform cylindrical appearance. Specifically, the outer surface of the yarn is deformed, such as by having undulations, mounds and/or depressed areas along the length of the yarn. The deformed shape of the outer surface of the yarn results in the yarn having a more natural look to that of real wicker. It is also known to provide the exterior surface of the polymer yarn with one or more random stripes of a contrasting color and/or one or more random grooves. The stripes and grooves can be continuous and/or intermittent along the exterior surface of the yarn. The yarn, however, can also have a more uniform cylindrical shape, as well as other shapes such as square, oval, flat, triangular and the like. Polymer yarns as thus far described are known from U.S. Pat. Nos. 5,704,690, 5,845,970 and 6,179,382; as well as U.S. Design Patent Nos. 395,171, 474,614 and 409,001; the disclosures of which are incorporated herein by reference. As in the case of natural wicker, polymer yarns have been woven into a woven material, which has been used in the manufacture of casual furniture suitable for the outdoor furniture market, including patio furniture, as well as for indoor use.
There is known twisted composite yarns for use in manufacturing synthetic woven material for furniture articles in Applicant's U.S. Pat. Nos. 6,625,970, 6,705,020 and 6,725,640, the disclosures of which are incorporated herein by reference. These patents disclose various methods of heat setting multiple strand twisted yarns and forming same into a woven material for use in forming, for example, seat and back portions of a furniture article. The twisted yarns are used as both the weft yarns and the warp yarns to form the woven portion, which is adhered to a frame of a furniture article. There is also disclosed the application of multiple strands twisted and single strand non-twisted synthetic yarns for use in manufacturing synthetic woven material for furniture articles in Applicant's co-pending application Ser. No. 10/158,629, entitled “Combination Weave Using Twisted and Non-Twisted Yarn” which was filed on May 30, 2002, the disclosure of which is also incorporated herein by reference. This latter application discloses various methods of providing a more comfortable seat portion through the use of non-twisted yarn strands as the warp yarns.
The aforementioned also disclose forming a weave from various combinations of twisted and/or non-twisted synthetic yarns which are adhered prior to or after the weaving process to the frame of an article of furniture. The woven synthetic material is subsequently heat set by placing the article of furniture having the weave thereon into an oven in accordance with the disclosed process. The heat setting process stabilizes the weft and warp yarns to inhibit their shifting within the weave, as well as heat setting individual twisted strands of polymer yarn which may be used as the weft and warp yarns. It has been observed, however, that the heat setting process results in elongation of the polymer strands causing sagging of the woven panels particularly in the seat and back rest portions which span an unsupported area of the article frame. Although the slight sagging of the polymer woven material does not affect the usability of the furniture article, it detracts from the aesthetic appeal of the article to the consumer.
It is therefore desirable to provide improvements in the manufacture of polymer woven material for use in furniture articles and accessories therefore including, for example, the use of twisted strands of polymer yarn and heat set woven material therefrom.